Shifting system for walking supports

ABSTRACT

A shifting system for a walking support of the type comprising two successive piers coupled to a common shift beam situated ahead of said piers. For connecting each of said piers to said beam, a shift rod is pivotally connected on the one hand to the lower frame of said pier and on the other hand to said shift beam. A first shift jack is pivotally connected to the one hand to said lower frame and on the other hand to said rod. A second shift lock is pivotally connected on the one hand to said shift beam and on the other hand to said shift rod.

I Jnited States Patent [191 Alacchi 1 Dec. 24, 1974 1 SHIFTING SYSTEMFOR WALKING SUPPORTS [76] Inventor: Georges Alacchi, 9 ter coursFauriel,

[52]v U.S. Cl 61/45 I) [51] Int. Cl .L E21d 15/44 [58] Field of Search61/45 D, 45 C, 63; 299/11,

830,342 3/1960 Great Britain 61/45 D 957,071 5/1964 Great Britain 61/45D 1,213,019 11/1970 Great Britain 61/45 D Primary Examiner-Dennis L.Taylor Attorney, Agent, or Firm-Dennison, Dennison, Townshend & Meserole[57] ABSTRACT A shifting system for a walking support of the typecomprising two successive piers coupled to a common shift beam situatedahead of said piers. For connecting each of said piers to said beam, ashift rod is pivotally connected on the one hand to the lower frame ofsaid pier and on the other hand to said shift beam. A first shift jackis pivotally connected to the one hand to said lower frame and on theother hand to said rod. A second shift lock is pivotally connected onthe one hand to said shift beam and on the other hand to said shift rod.

4 Claims, 3 Drawing Figures PATENTED DEB24I974 SHEET 1 OF 2 BACKGROUNDOF INVENTION It is standard practice in the mining industry and, inparticular, in coal workings to couple several supporting piers to oneand the same shift beam with a view to successively and alternatelyshifting each of said piers at a rate commensurate with the rate ofadvance whilst the adjacent pier(s) maintain their pressure on the roofin their respective work zones.

Unfortunately, these known systems all have the disadvantage of beingrelatively sensitive to the slope of the workface. Accordingly, it isdifficult by means of these systems to ensure advance in a specificgeometric direction.

BRIEF SUMMARY OF INVENTION The object of the invention is thus toprovide a shift system for walking supports for coal mines which, on theone hand, enables workings to advance in a precise horizontal directionperpendicular to the line of maximum inclination of the workface and, onthe other hand, enables the shift beam of the system to be displacedparallel to itself.

According to the invention, this object is achieved through a shiftsystem for walking supports of the type comprising at least twosuccessive piers coupled to'one and the same shift beam situated aheadof said piers, distinguished by the fact that, for connecting each ofsaid piers to said beam, it comprises a shift rod pivotally connected onthe one hand to the lower frame of said pier and, on the other hand, tosaid shift beam and two shift jacks of which the first is pivotallyconnected on the one hand to the lower frame and on the other hand tosaid rod, whilst the second is pivotally connected on the one hand tosaid shift beam and on the other hand to said shift rod.

This arrangement shows a first advantage of the invention because, byvirtue of the geometric configuration advantageously adopted forconnecting each of the piers of the walking support to the shift beam bymeans of the shift rod and the two shift jacks, it is very easy tosatisfy the two requirements referred to above at one and the same timeand, hence, to avoid the disadvantages normally encountered inconventional systems.

Other features and advantages of the shifting system according to theinvention will become apparent from the following description, givenpurely by way of example, of one embodiment of this system inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS These piers are piers of any knowntype, for example comprising an upper frame 4 connected toa lower frame5 through at least two props 6 and 7, and a connecting jack 8 and,optionally, other components such as sets of rods pivotally connected tosaid frames or other props (not shown). Each of the upper frames 4carries a cowl 9 pivotally connected to said upper frame about twoaligned axes 10 and 11, the cowls 9 being themselves each provided witha cushion 12 of water under pressure.

The present invention is essentially embodied in the nature andarrangement of the components by which each of the piers l and 2 of thewalking support are connected to the shift beam 3.

For each of these piers, this connection is established through a shiftrod 13 pivotally connected on the one hand at one of its ends about anaxis 14 to a member 15 integral with the upper frame 5 of the pier and,on the other hand, at its other end, about an axis 16 to a member 17integral with the shift beam 3, the two axes 14 and 15 being parallel toone another and perpendicular to the plane of the lower frame 5 and ofthe shift beam 3.

In addition, a first double-acting shift jack 18 is pivotally connectedonthe one hand to the lower frame 5 aboutan axis 19 at one of its ends,and, on the other hand, to the shift rod 13about an axis 20 at its otherend, these two axes l9 and 20 being parallel to one another and to theaxes 14 and 16.

Similarly, a second double-acting shift jack 21 is pivotally connectedon the one hand to the shift beam 3 about an axis 22 at one of its endsand, on the other hand, to the shift rod 13 about an axis 23 at itsother end, these two axes 22 and 23 again being parallel to one anotherand to the axes 14, 16, 19 and 20.

The fixed distance between the axes 14 and 19 is designed to be equal tothe similarly fixed distance between the axes 16 and 22.

Similarly, the two fixed distances between the axes 14 and 20 andbetween the axes 16 and 23 are designed to be equal.

Thus, since the two shift. jacks 18 and 21 are themselves equal inlength in each of their positions, the two jacks being fed withidentical quantities of fluid through a known'feed system (not shown),it can be seen that the two triangles formed respectively in the planeof the Figure by the axes l4, l9 and 20 and by the axes 16, 22 and 23will always remain equal and homothetic relativeto the centre. of theshift rod 13, and that, accordingly, through a simple property ofgeometry both the shift beam 3 and the supporting piers 1 and 2 will bedisplaced during shifting parallel to FIG. 1 is a view from above, indiagrammatic section I on the line lI of FIG. 3, of the entire shiftingsystem DESCRIPTION OF PREFERRED EMBODIMENT As can be seen from FIG. 1,the shifting system for walking supports according to the inventionconsists of two piers l and 2 coupled to a common shift beam 3.

themselves.

In addition, if, shown in broken lines in FIG. 1, care is taken toprovide an angular movement for the shift rod 13 such that these twoinitial andfinal end positions are symmetrical one with the otherrelative to the straight line 24 intersecting the axis 14 and parallelto the direction of maximum slope 25 of the workface, it will readily beappreciated that the end positions in the movement corresponding to eachof the points of the shift beam 3 will be situated on a common lineperpendicular to the direction of maximum inclination 25, i.e. from ahorizontal line.

Accordingly, the shift beam 3 is shifted by acting on the jacks of onepier, for example the pier l, by delivering the same quantity of fluidto the two jacks l8 and 21 in known manner, the two identical jacks ofthe pier 2 being at exhaust, so that the shift beam 3 is brought intothe position shown in chain-lines in FIG. 1. The piers are shifted inturn in a second stage, the shift beam 3 having been advanced asdescribed above.

For this purpose, the shift beam 3 being fixed in position by lockingthe jacks 18 and 21 of the pier 1 held in its braced position by itsprops 6 and 7, the pier 2 is initially advanced after having beenloosened (the initial position of this pier is shown in chain-lines inFIG. 2) by retracting the two jacks l8 and 21 of the pier 2, equal inlength, by delivering the same quantity of fluid to the minor face ofthe two jacks l8 and 21 of the pier 2. When the pier 2 arrives in itsfinal position, after having made a translation represented by thetrajectory 26 of a peak 2a of the pier 2, shown in chain-lines in FIG.2, it is tightened up, and the same procedure is adopted for shiftingthe following piers.

In addition, the shift beam 3 can carry one or more props 27 designed toreinforce the application to the roof of a known type of shield (notshown) pivotally mounted on the front of the upper frame of each of thepiers.

The invention is by no means confined to the embodiment described purelyby way of example in the foregoing, instead it covers any modificationincluded within the scope of the following Claims.

I claim:

1'. A shifting system for a walking support of the type comprising twosuccessive piers coupled to a common shift beam situated ahead of saidpiers, the improvement comprising means, for connecting each of saidpiers to said beam, said means comprising a shift rod pivotallyconnected on the one hand to thc lowerframc of said pier and on theother hand to said shift beam, and two shift jacks of which the first ispivotally connected on the one hand to said lower frame and on the otherhand to said rod, whereas the second is pivotally connected on the onehand to said shift beam and on the otherhand to said shift rod.

2. A shifting system for walking supports as claimed in claim 1, wherein the distances of each of the pivotal connections of one of the twoshift jacks to the pivotal connection of the rod to the lower frame areequal and opposite in direction to those separating each of the pivotalconnections of the other shift jack from the pivotal connection of therod to the shift beam.

3. A shifting system for walking supports as claimed in claim 2, wherein the shift beam comprises a connecting jack arranged in the axis ofsaid beam, its piston head being connected to the adjacent beam througha connecting chain.

4. A shifting system for walking supports as claimed in claim 3, wherein the shift beam carries at least one prop intended to reinforceapplication to the roof of a shield pivotally mounted on the front ofthe upper frame of each pier.

1. A shifting system for a walking support of the type comprising twosuccessive piers coupled to a common shift beam situated ahead of saidpiers, the improvement comprising means, for connecting each of saidpiers to said beam, said means comprising a shift rod pivotallyconnected on the one hand to the lowerframe of said pier and on theother hand to said shift beam, and two shift jacks of which the first ispivotally connected on the one hand to said lower frame and on the otherhand to said rod, whereas the second is pivotally connected on the onehand to said shift beam and on the otherhand to said shift rod.
 2. Ashifting system for walking supports as claimed in claim 1, where in thedistances of each of the pivotal connections of one of the two shiftjacks to the pivotal connection of the rod to the lower frame are equaland opposite in direction to those separating each of the pivotalconnections of the other shift jack from the pivotal connection of therod to the shift beam.
 3. A shifting system for walking supports asclaimed in claim 2, where in the shift beam comprises a connecting jackarranged in the axis of said beam, its piston head being connected tothe adjacent beam through a connecting chain.
 4. A shifting system forwalking supports as claimed in claim 3, where in the shift beam carriesat least one prop intended to reinforce application to the roof of ashield pivotally mounted on the front of the upper frame of each pier.